1. Field of the Invention
The invention relates to systems for the irrigation and/or aspiration of fluids into or from a surgical work site during an endoscopic procedure. More particularly, the invention relates to a multi-purpose irrigation/aspiration system for use during minimally invasive surgery for the purpose of performing any one of a variety of irrigation/aspiration functions such as, for example, tissue lavage, joint distension or uterine distension. Still more particularly, the invention relates to an irrigation/aspiration system having a common control system operating two separate pumps, one pump dedicated to irrigation and one pump dedicated to aspiration. Still more particularly, the invention relates to a method for calculating joint pressure at the surgical site using measured and calculated pressure and fluid flow parameters.
2. Description of the Prior Art
Minimally invasive surgery, also referred to herein as endoscopic surgery, often utilizes an irrigation system to force suitable biocompatible fluid into the area surrounding the surgical work site within a patient. The term “irrigation” is used broadly to mean any type of pressurized fluid flow whether it be for irrigation in particular or for other uses described below. Flexible plastic tubing is used to conduct the fluid from a source to the work site and from the work site to a drain or other receptacle. Flexible tubing is also sometimes used as a pressure monitoring line to convey fluid pressure information to a control mechanism. Depending upon the procedure, the irrigating fluid is useful for various purposes such as tissue lavage, hydro-dissection, joint distension, uterine distension, etc. Known irrigation systems include electrically driven pump systems, in which a suitable fluid is pumped through flexible tubes from a source to the work site, gravity-feed systems, in which the pump is replaced by merely adjusting the height of the fluid supply above the patient, and nitrogen powered systems.
Irrigation systems generally utilize a means to set the pressure desired at the surgical work site. A feedback loop uses information from a pressure sensor to maintain the set pressure within a desired range. The invention described herein includes improvements in pressure control.
Known aspiration systems employ a source of reduced-pressure (i.e. lower than that of the work site) and include vacuum systems, in which a vacuum source is simply connected via flexible tubes to the work site, and simple gravity controlled drain lines. Aspiration of the fluid serves to either simply remove it to improve visibility, prevent undesirable fluid accumulation or high pressure at the work site, or to regulate the flow rate to maintain a predetermined fluid pressure at the work site.
Because the irrigation and aspiration functions are commonly used together, prior art irrigation/aspiration systems have been developed to perform both functions with one system, often combined in one console which provides power and control. The irrigation system is generally used in conjunction with an aspiration system which removes the fluid pumped into the work site at a controlled rate depending on the flow rate selected by the surgeon. Dual pump irrigation and aspiration systems are known where one pump is dedicated to the irrigating function and another pump is dedicated to the aspirating function. Each system utilizes a collection of flexible tubes to connect the fluid and vacuum sources to appropriate instruments inserted into the body. The collection of tubes includes a fluid inflow conduit, a fluid outflow conduit and, in some instances, a pressure monitoring conduit. All of the tubes are packaged together as a tubing set and each tubing set is produced as a unit containing all necessary tubes and connections required for performing a particular procedure with a particular system. This invention relates to improvements in dual pump irrigation/aspiration systems.
Consequently, it is an object of this invention to produce an irrigation/aspiration system having an inflow pump and an outflow pump and a control system for operating each pump in accordance with predetermined characteristics defined for use during a selected one of several different surgical procedures.
It is also an object of this invention to produce a multi-purpose irrigation/aspiration system capable of operating with a variety of specific types of tubing sets, each set intended for use only during a particular type of surgical procedure.
It is also an object of this invention to produce a multi-purpose irrigation/aspiration system capable of operating with a variety of specific types of tubing sets which are each identified with a particular coding means associated with that tubing set type to identify the use for which the tubing set and/or the system associated therewith is intended.
It is also an object of this invention to produce two tubing cassettes for use with a multi-purpose irrigation/aspiration system wherein one cassette is dedicated to and facilitates the engagement of the irrigation tubing with the system and the other cassette is dedicated to and facilitates the engagement of the aspiration tubing with the system.
It is still another object of this invention to produce a dual pump irrigation/aspiration system having a flow control system which automatically changes the outflow of fluid based on whether another tool, such as a shaver blade handpiece is activated to withdraw additional fluid from a surgical work site.
It is yet another object of this invention to produce a dual pump irrigation/aspiration system having varying size peristaltic rollers and associated tubing cassettes to facilitate proper assembly.
It is also an object of this invention to produce a dual pump irrigation/aspiration system having a flow control system capable of controlling selectively pressure and flow on the basis of actual intra-articular pressure or a calculated/inferred pressure.
It is also an object of this invention to produce a dual pump irrigation/aspiration system having a valve means and a control for the valve means capable of drawing outflow fluid from selected outflow tubes.
It is yet another object of this invention to produce a dual pump irrigation/aspiration system having a software driven declogging feature.